[PATCH] D49276: [InstCombine] Corrections in comments for division transformation
Sanjay Patel via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Sun Jul 15 10:12:07 PDT 2018
This revision was automatically updated to reflect the committed changes.
Closed by commit rL337131: [InstCombine] Corrections in comments for division transformation (NFC) (authored by spatel, committed by ).
Repository:
rL LLVM
https://reviews.llvm.org/D49276
Files:
llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
Index: llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
===================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -628,7 +628,7 @@
return Overflow;
}
-/// True if C2 is a multiple of C1. Quotient contains C2/C1.
+/// True if C1 is a multiple of C2. Quotient contains C1/C2.
static bool isMultiple(const APInt &C1, const APInt &C2, APInt &Quotient,
bool IsSigned) {
assert(C1.getBitWidth() == C2.getBitWidth() && "Constant widths not equal");
@@ -714,15 +714,15 @@
APInt C1Shifted = APInt::getOneBitSet(
C1->getBitWidth(), static_cast<unsigned>(C1->getLimitedValue()));
- // (X << C1) / C2 -> X / (C2 >> C1) if C2 is a multiple of C1.
+ // (X << C1) / C2 -> X / (C2 >> C1) if C2 is a multiple of 1 << C1.
if (isMultiple(*C2, C1Shifted, Quotient, IsSigned)) {
auto *BO = BinaryOperator::Create(I.getOpcode(), X,
ConstantInt::get(Ty, Quotient));
BO->setIsExact(I.isExact());
return BO;
}
- // (X << C1) / C2 -> X * (C2 >> C1) if C1 is a multiple of C2.
+ // (X << C1) / C2 -> X * ((1 << C1) / C2) if 1 << C1 is a multiple of C2.
if (isMultiple(C1Shifted, *C2, Quotient, IsSigned)) {
auto *Mul = BinaryOperator::Create(Instruction::Mul, X,
ConstantInt::get(Ty, Quotient));
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